Micrometer reading attachment



1952 J. KAWABATA MICROMETER READING ATTACHMENT Filed Nov. 12, 1949Patented Nov. 18, 1952 UNITED STATES TENT OFFICE 3 Claims.

This invention relates to a new and improved scale reading device.

It is, and always has been, extremely diificult to accurately measuredistances and in the accomplishment of such measuring the aligning ofone line with another line is necessarily most exacting. Considerableerror is caused by parallax when the lines to be matched are not in thesame plane. Irregularities in the ends of the lines to be aligned canalso cause considerable error when measurements to ten-thousandths of aninch are desired. It is with these minute measurements that the presentinvention is concerned.

An important object of this invention is to provide means in a scalereading device for accurately aligning opposed lines.

Another important object of this invention is the provision of asighting device associated with and facilitating scale reading.

Another and further important object of this invention is to supplysighting means for a scale reader which automatically compensates forhuman operator error in viewing the scale and commonly known asparallax.

A further object of this invention is to provide a sighting mechanismfor aligning an inscribed line on a movable member with an inscribedline on a stationary member.

A still further object of this invention is the provision of a sightingattachment for scale readers in which a transparent or partiallysilvered mirror is positioned midway between the movable and fixed lineswhereupon the lines may be accurately superimposed by the viewer with aminimum of effort.

Another and still further important object of this invention is toprovide a scale reading device including a movable drum having acircumferential line inscribed therearound and means for aligning thiscircumferential line with a 1ine on a stationary member and opticalmeans to accomplish such aligning by superimposition of the one line onthe other.

Other and further important objects of this invention will becomeapparent from the disclosures in the following specification andaccompanying drawings.

In the drawings:

Figure 1 is a front elevational view of the micrometer readingattachment of this invention.

Figure 2 is an end elevational view of the device as shown in Figure 1.

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a diagrammatic view of the optical operation of the sightingmechanism.

As shown in the drawings:

The reference numeral I indicates generally a support upon which themicrometer I I is mounted. Positioned adjacent the support Ill is ascale I2 having inscribed spaced lines I3, which lines are numericallynumbered as shown. It is the function of this device to measure therelative longitudinal movement that may occur between the elements I!)and I2. Either one of the elements I0 or I2 may be made stationary andthe other part or element may move longitudinally with respect thereto.Thereafter the micrometer II may be adjusted to show how much the one orother element has been moved. Assume, for example, that the element I0remains fixed and that the scale I2 is moved slightly in one direction.The micrometer is then adjusted to compensate for the movement of thescale I2 and a reading may be had directly on the micrometer to showexactly how much the scale I2 was previously moved.

The support I0 includes a first post or micrometer bracket I4 and alaterally spaced post I5. The micrometer II consists of a supportingshell or housing I6 for fixed mounting within the bracket I l, arotating drum I1, and a longitudinally extensible and rotatable memberI8 which forms a lateral extension of the rotating drum I'I beyond thefixed part I6. A micrometer is, of course, an instrument to measuresmall distances and it accomplishes this by a calibrated scale I9,annularly positioned around the movable drum I1, and a longitudinallyextending scale 20, inscribed on the fixed member I6. Both of thesescales I9 and 20 bear a definite relationship to the pitch of thethreads employed within the instrument. Thus, if the rotatable drum I!is rotated a certain distance the member I8 will be extended apredetermined distance from the fixed part I6 of the micrometer. Themicrometer II is attached to the element I0 by means of the integralbracket I 4 which has a sleeve-like micromoter holding portion 2 I.

The micrometer extensible member I8 is provided with a reduced diametershaft extension 22. A cylindrical drum member 23 is mounted on and fixedto said shaft extension in abutting relationship with the shoulder 24 ofthe member I8. The drum 23 has inscribed around the center thereof anannular line 25. The drum 23 thus rotates and shifts simultaneously withthe extensible member I8, and it is the annularly inscribed line 25 onthe drum which is aligned with one of the inscribed lines I3 on thescale I2.

The micrometer is additionally provided with sighting means throughwhich the lines 25 and I 3 are superimposed by particular means toelimihate the human error both in the inscribing of the lines, and theerror of aligning one line with another. This sighting means includes alens member 26 carried in a bracket 27, which in turn is mounted bymeans of a sleeve member 23 on the extension'shaft 22 beyond the end ofthe drum 23. An outwardly extending annular flange 29 on 23', inasmuchas the bracket 21 carrying the lens.

26 is arranged and constructed to move with the drum 23. The sleeve 28is loosely carried on the shaft extension 22 in order to permit rotationof the shaft 22 without tending to rotate the lens holder.

A half silvered or transparent mirror 30 is provided in a positionbetween the lens 2% and the scale I 2. The half silvered mirror 30 iscarried by the spaced posts 14 and ['52 on. the

support Hi. The attachment of. the mirror to thepost I4 is shown at 3|.in Figure: 3: and' to the post l5 at 32- in" Figure 2. The transparentmirror 30 is ofa type-now commercially available and includes a mirrorcoating at 33 which is thin enough to be transparent. Glass. platemembers 3.4 and 35 enclose the mirror coating 33, thus protecting itagainst damage either-by abrasion in cleaning or other possiblescratching. as. well asto delay oxidation of. the metal coating. Thevery thin mirror coating 33 permits transmission of sight as wellasreflection,. and thus isv ideally suited for the particular applicationof this invention.

The lens bracket 21 is: provided with a foot or spacer member 36arranged and constructed to slide on the surface: of the mirror 30:during micrometer adjustment. The looseness: of the sleeve 28 on the.shaft 22 permits gravity'to'hold the lens bracket foot 36 against themirror thus maintaining a fixed spacing between lens and mirror forproper and constant focus of the scale and drum.

It should be noted that the transparent mirror 30 ispositioned exactlymidway between the drum 2.3 and the scale I2 An' operator or user ofthis device views the scales, that is the inscribed lines I3, onthescale member I2 and simultaneously the annularly inscribed line 2-5 onthe drum 23 by viewing through the lens'26. The operators sight ispermitted to travel directly through the transparent mirror 3!) to thescale l2 and simultaneously toreflect from the transparent mirror 30'tothe drum 23;

In order to completely understand the operation of the device; it wasbelieved desirable to indicate the position of the operators orusers eyeand this is shown at 3-1- in diagrammatic Figure 4. The operator directshis vision as shown in Figure 4 through the-lens 2-6 and there'- uponsimultaneously uses the scale 12 and the drum. 23... The drum 23 isaxially shiftableby means of the micrometer hand rotor l1 and asaresult. the annular line- 25 may be moved until it aligns itself withone of the scale inscribed lines l3 on the scale Ill. The distancesdesignated by the letters X and Yale the same length. In. other words,as the operator views the inscribed lines l3 and 25,. they are ineffect: in one plane. As longasthe inscribed lines to, be superimposedarein: the same plane for all effects, then; parallax is not aproblem.to contend; with in. this device. Parallax is any apparent displacementof an; object due to an. observers position. In this sighting device theobserver or operatorma-y move his sighting position throughout aconsiderable angle before he materially affects: his. reading. Theannular line 25 on the drum 23 can be superimposed very accurately onany one of the lines [3 on the scale l2 because the lines can be split.On the conven= tional vernier the lines must be matched and thus anylocal errors in the. line. may affect the reading. By splitting thelines, any variation in width of the lines has little efiect and anysmall bumps or waves in the lines may be detected and disregarded. Splitline accuracy instead of matched line. accuracy and elimination ofparallax account for a high degree of accuracy of this instrument. Thelens 26 which may be plural is' generally to be provided with amagnification making the superimposing of the lines easier for theoperator. A light bulb 38 located above the lens and transparent mirrorand positioned substantially between these two elements is provided forillumination of these elements to. facilitate reading. Thebulb 38preferably e ectricis; mounted: in a; socket. 39. The socket 39' is:held by a clamp; 40; projecting upwardly from the: bracket: Id. Asuitable source ofelectrical energy is delivered to. the lead. wires 3|to cause illumination. of the bulb 38. The superimposing of. the scaleline on the drum line is made very accurate.- by: a combination ofmagnification by; the lens. 21, illumination by the bulb 33, eliminationof parallax, having split line accuracy in utilizing the full drum lineand the fullscale line-in their'entireties; so that inaccuracies in anyportion or portions of these lines may be eliminated- Scale: reading isalso facilitated: by the psychological. centering action obtained as-theeyeof. the operator automatically tends to superimpose the. scale lines.

In constructing the; device the shaft H3. and drum 23 should beaccurately concentric in order thatthere shall bev nowobble. Further, tomake reading of the instrument easier it is. desirable to have the drumsurface entirely black and the annularly' inscribed line white so thatthe superimposing ofone of the black scale lines i3 on the annular whiteline 25 will be made considerably easier. It should be understood thatit is not essential to have this annular drumline white butrather onlythat white facilitates the alignment ofthe lines [-3- and 2-5. The glassplates 34. and 35 of the. mirror 30 will cause a deflection in the;sight lines of the observer due to. the refractive index of the mirrorglass. However, in view of the fact that the instrument will operateregardless. of the index of refraction of the mirror glass, it. has beendeemed advisable not. to'obscure. thev invention asset forth herein bydescribing these. minute ofisetsin observation lines. The device worksidentically regardless of whether or not. the index of refraction istaken into account.

There are numerous applications to whichv this instrument. may beapplied... As an example, the. instrument may be. used as a heightgauge, or may bev used on milling machines 01' small jig bores toaccurately measure change or relative change of positions of twoelements. In a heightv gauge it. is possible to obtain considerableaccuracy with the instrument of this invention which will mean. thatmany layout and gauging operations may be performed" without the. use ofgauge. blocks. Further, when the instrument is used on a milling machineor other similar machine it has an. advantage that no length stand ardsare necessary and the machine table can be jarred or moved at any speedwithout damage to the measuring elements. It is preferable that thedevice be properly housed depending upon its particular application.

5 It is believed that herein is provide a novel measuring apparatus witha sighting means that is practically infallible for any operator.Numerous details of construction may be varied throughout a wide rangeand this device may be used in numerous applications without departingfrom the principles disclosed herein, and I therefore do not proposelimiting the patent granted I hereon otherwise than as necessitated bythe appended claims.

What is claimed is:

1. A measuring apparatus for measuring the,

separation between spaced lines and utilizing a member having at leastone straight line inscribed thereon comprising a support positionedclosely adjacent said member, an axially movable drum member having acircumferential line inscribed about the periphery thereof and carriedon said support so that the axis of the drum is substantially parallelto said member and the plane formed by the circumferential line isparallel to the inscribed line on said member,means for moving said drummember longitudinally along said support by rotating said drum member,and I a sighting means for accurately aligning said f circumferentialline with the straight line on said member, said sighting meansincluding a transparent mirror disposed between said mem her and themovable drum member whereby the operators eye may simultaneously viewboth the line on said member and the circumferential line on the drumfor easy superimposing the one on the other and relative movementbetween said member and said drum may be accurately deter-l mined.

2. A measuring apparatus for measuring the separation between spacedlines and utilizing a relatively flat scale with spaced lines inscribedthereon, comprising a supporting structure spaced relatively easy andpositive. s

from said scale and carrying a drum having an annularly inscribed linetherearound, the plane of said annular line being parallel to the spacedlines inscribed on the flat scale, means for moving said drumlongitudinally of said flat scale,

a half silvered mirror positioned between said fiat scale and said drum,a lens mounted on said movable drum and directed on said half silveredmirror and said flat scale, whereby the lines on the flat scale and theannular line on the drum may be readily simultaneously viewed throughthe lens and the superimposing of the drum line on any one of the lineson the flat scale is made 3. A measuring apparatus as set forth in claim2 in which the half silver-ed mirror is disposed exactly midway betweenthe flat scale and the drum whereby accurate superimposing of the drumline on one of the flat scale lines may be accomplished despite variedangular sighting through the lens.

JAMES KAWABATA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS I Date

